1. Field of the Invention
The present invention relates to a battery module, and more particularly, to a battery module having a plurality of unit batteries for which cooling efficiency is improved.
2. Description of the Related Art
Unlike a primary battery, a rechargeable battery may be recharged. Low capacity batteries are used for various portable electronic devices such as phones, laptop computers, and camcorders. High capacity batteries are used as the power source for driving motors, such as those for hybrid electric vehicles.
Depending on their external shape, rechargeable batteries may be classified into different types, for example, prismatic and cylindrical batteries. The high capacity rechargeable battery (hereinafter, referred as “battery module”) are composed of a plurality of rechargeable batteries (hereinafter, each referred as “unit battery”) so that it can be used to drive motors of machines requiring a high power source such as hybrid electric vehicles.
Each of the unit batteries includes an electrode assembly having positive and negative electrodes and a separator interposed between the positive and negative electrodes, a case for receiving the electrode assembly, a cap assembly for sealing the case, and positive and negative terminals extending from the cap assembly and electrically connected to the positive and negative electrodes, respectively.
In the battery module, the unit batteries are spaced apart from each other by a predetermined distance and connected in series or parallel.
Since the battery module is comprised of several to tens of unit batteries, the heat generated from the unit batteries must be efficiently dissipated. The heat dissipation property of the battery module is a very important factor on which the performance of the battery module depends.
When the heat dissipation is not properly realized, a temperature difference between the unit batteries may be generated to deteriorate the charge/discharge efficiency. Furthermore, the temperature of the battery module may increase excessively, thereby deteriorating the performance of the battery module or, in the most severe cases, causing the explosion of the battery module.
Particularly, when the battery module is used as the high capacity rechargeable battery for driving motors of, for example, a vacuum cleaner, an electric scooter, or a hybrid electric vehicle, the charge and discharge is done with a large capacity of current. Thus, the internal temperature of the battery module increases excessively. This deteriorates the inherent performance of the battery module. Therefore, it is very important to efficiently dissipate the excessive heat out of the battery module.